Abstract: Perioperative mortality has long been a concern. Although the intraoperative mortality rate has made a 10-fold reduction in the past 3 decades, the thirty-day postoperative mortality rate remains high. Patients die because signs of deterioration are missed. Deterioration of patients is often overlooked or not detected at all. One of the reasons is that the intensity of nursing and the frequency of monitoring vital signs are decreased from the Intensive Care Unit via wards to home. Early detection of physiological instability is crucial to prevent death and disability. Therefore, perioperative continuous monitoring of vital signs and other information is crucial to detect physiological instability and may have the potential benefit to reduce the perioperative mortality and the incidence of major postoperative complications. Wearable continuous vital-sign monitors are expected to achieve this vision. Nowadays this kind of device is available, but further research on it is still needed. This article reviewed the current status of vital-sign monitoring and the value of wearable vital-sign monitors during the perioperative period.